Primary care practices have access to the majority of the population at risk for chronic illness, so that registered nurses represent an untapped resource to prevent complications and modify the course of chronic disease. Nurses and physicians spend a lot of time together and yet, often do not share vital insights about their patients and their practice. The adaptation of primary care practices to increasingly complex chronic care needs of patients may in part depend on the quality of the relationships among practice members (i.e. nurses and physicians). Primary care practices can be viewed holistically by seeing them as complex adaptive systems in which the interrelationships of nurses and physicians help determine what will be successful for patients and the practice. A major contribution of research on complex adaptive systems has been to develop ideas that help us see the sources and consequences of distinctive interaction patterns among people. Patterns of interactions can help explain why some systems function more effectively and adapt to their environment better than others. The study aims to: 1) describe the presence of social capital (i.e. trust, reciprocity, and cooperation), and 2) describe the presence of movement in conceptual space (i.e. information flow) among nurses and physicians, in primary care practices and determine their association with standards of chronic illness care. The above aims will be addressed using data from a group randomized clinical trial of family practices in New Jersey. Baseline information from the first twenty practices serves as the data for this study. This data will be obtained using a practice-based observational data process called the Multimethod Assessment Process (MAP). MAP has been developed for understanding the unique barriers, opportunities and complexity of diverse primary care practice settings. A comparative case study analysis will identify features of relationships among nurses and physicians in primary care settings that are associated with utilization of standards for chronic illness care.